Hi there:
I am running Plex Media Server on a Seagate PersonalCloud, 4TB NAS.
I have been able to import my music to a library. Artists, track titles and albums are properly indexed. However, the genre tags are only partially recognized. Why is that?
Here is an example from MusizBrainz. The band James is indexed with the genre Brit Pop and it is all .mp3 files. the band Echo & the Bunnymen is not indexed with any genre in PlexMedia, but in MusicBrainz, it is. It is made up of .m4a files. 
Currently, the option "use embedded media tags" is checked , the library agent is "personal media artists" . Also: under "servers > Agents > Artists" "Local media - artists" is checked and prioritized first. Can any one provide any advice?